1. Field of the Invention
The present invention relates to a sheet post-processing apparatus, an image forming apparatus, and an image forming system including the sheet post-processing apparatus and the image forming apparatus.
2. Description of the Related Art
A sheet post-processing apparatus is widely used for performing post-processing, such as sorting, stapling, or stacking of sheets (printing sheets) received from an image forming apparatus, such as a copy machine or a printer. The sheet post-processing apparatus is, for example, a sorter or a finisher. The sheet post-processing apparatus is arranged downstream of the image forming apparatus.
For example, in Japanese Patent Application Laid-open No. H10-059610 and Japanese Patent Application Laid-open No. H11-060038, technologies of such a sheet post-processing apparatus are disclosed in which a plurality of sheets conveyed to a staple tray in the sheet post-processing apparatus is aligned in a conveying direction by putting an edge of each of the sheets in contact with a rear-end fence arranged on a lower portion of the staple tray, and a discharging claw then directly scoops up the pile by supporting an edge of a pile of the sheets, thereby discharging the pile out of the staple tray.
In Japanese Patent Application Laid-open No. H10-059610, the pile of the aligned sheets is directly scooped by the discharging claw, and is discharged out of the staple tray. In Japanese Patent Application Laid-open No. H11-060038, the discharging claw is moved to a position near the pile, and stands by at that position. The discharging claw is then moved to a corresponding scooping position to directly scoop up the pile, thereby discharging the pile out of the staple tray.
In the conventional technologies, however, especially, when a plurality of Z-folded sheets is conveyed to the staple tray, a folded portion of each of the Z-folded sheets interferes with the rear-end fence arranged at the lower portion of the staple tray. Therefore, it is difficult to align the Z-folded sheets on the staple tray.